1. Field of the Invention:
The present invention relates generally to static structures, particularly traffic-carrying surfaces, such as helicopter landing pads.
2. Description of the Related Art:
Helipads used for both civilian and military applications have usually consisted of an asphalt or concrete substrate that is coated with urethanes of various colors to form a predetermined pattern. The urethane coatings are generally applied just 8 mils (8/1000 of an inch=0.203 millimeters) thick and, consequently, provide no significant benefit other than clearly marking a landing zone.
With a desire for a more permanent and consistent surface, nonloose fill surfaces in the nature of processed particles bonded together in some fashion were developed to be installed over hard surfaces, such as concrete and asphalt. Nonloose fill surfaces, which are generally referred to as synthetics, can be divided into two main categories: systems with seams and systems without seams. Examples of systems with seams or socalled nonseamless systems are shown in Donovan U.S. Pat. No. 4,557,457, Roby U.S. Pat. No. 3,846,945, Burke U.S. Pat. No. 3,251,076, Mitchell U.S. Pat. No. 2,999,431, and Stedman U.S. Pat. No. 957,387.
Both nonseamless and seamless surfacing systems have an attenuating element and a surface layer. This surface layer can be either installed in the field or integrated at the time of manufacture. However, the seamless systems have a texture coat of sealer and aggregate applied over the surface layer to form a monolithic arrangement. Seamless surfacing systems are becoming the more desirable of the synthetic systems because insects and rodents cannot enter and nest in them, nor can dirt and debris collect in the seams. An additional benefit of seamless surfacing systems is that water is not allowed to enter into the system.
Water, when introduced into the system, can cause structural deterioration and delamination of the surface system from its subbase.